<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            padding: 20px;
        }
        input[type="text"] {
            width: 100%;
            padding: 10px;
            font-size: 16px;
            border: 1px solid #ccc;
            border-radius: 4px;
            box-sizing: border-box;
        }
    </style>
</head>

<body>
    <input type="text" placeholder="请输入内容">
</body>

</html>